Inter-subject Variability of LTD-like Plasticity in Human Motor Cortex: A Matter of Preceding Motor Activation
Inter-subject Variability of LTD-like Plasticity in Human Motor Cortex: A Matter of Preceding Motor Activation
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DOI：
10.1016/j.brs.2014.08.004
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发表时间：
2014-11-01
影响因子：
7.7
通讯作者：
Ziemann, Ulf
中科院分区：
文献类型：
--
作者：
Goldsworthy, Mitchell R.;Mueller-Dahlhaus, Florian;Ziemann, Ulf
背景：人类初级运动皮层（M1）的连续θ波爆发刺激（cTBS）诱导皮质脊髓兴奋性的长期抑郁（LTD）样可塑性变化，但一些研究已经报道了这种效应的高度主体间变异性。大多数研究在cTBS之前使用目标肌肉的强直性随意收缩来设定刺激强度；然而，目前尚不清楚这可能如何影响反应变异性。目的：探讨靶手肌预激活对人体M1型cTBS反应变异性的影响。方法：采用右第一背骨间肌（FDI）运动诱发电位（MEP）振幅变化评价cTBS反应。在研究1中，10名健康受试者参加了两次会议。在一组中，他们被要求在整个测试期间保持FDI放松（预放松），在另一组中，在cTBS前15分钟进行2分钟的10%的最大自愿强直收缩（预活跃）。对于研究2，我们重新分析先前研究的数据，将预放松条件扩展到另外26名受试者（总n = 36）。结果：ctbs诱导的前放松状态下高一致性的ltd样MEP下降，而前活跃状态下不一致。受试者间反应变异性在前活跃状态下增加。结论：cTBS在避免被刺激的运动皮层的预激活的情况下，诱导了一致的ltd样可塑性和低主体间变异性。这证实了cTBS在降低皮质兴奋性的临床应用中的转化潜力。(C) 2014爱思唯尔公司版权所有。
Background: Continuous theta burst stimulation (cTBS) of the human primary motor cortex (M1) induces long-term depression (LTD)-like plastic changes in corticospinal excitability, but several studies have reported high inter-subject variability of this effect. Most studies use a tonic voluntary contraction of the target muscle before cTBS to set stimulation intensity; however, it is unclear how this might affect response variability.Objective: To examine the influence of pre-activation of the target hand muscle on inter-subject response variability to cTBS of the human M1.Methods: The response to cTBS was assessed by changes in motor evoked potential (MEP) amplitude in the right first dorsal interosseous (FDI) muscle. For Study 1, ten healthy subjects attended two sessions. They were instructed in one session to keep their FDI relaxed for the entire testing period (pre-relax), and in the other to perform a 2-min 10% of maximal voluntary tonic contraction 15 min before cTBS (pre-active). For Study 2, data from our previous study were re-analyzed to extend the pre-relax condition to an additional 26 subjects (total n = 36).Results: cTBS-induced highly consistent LTD-like MEP depression in the pre-relax condition, but not in the pre-active condition. Inter-subject response variability increased in the pre-active condition.Conclusions: cTBS induces consistent LTD-like plasticity with low inter-subject variability if pre-activation of the stimulated motor cortex is avoided. This affirms a translational potential of cTBS in clinical applications that aim at reducing cortical excitability. (C) 2014 Elsevier Inc. All rights reserved.